The Baeyer-Villiger oxidation of a model cyclic ketone, 2-adamantanone, using H2O2 as the oxidizing agent, was systematically studied using a range of metal triflates in toluene. The extremely high activity of Sn(OTf)(2) in promoting the oxidation, allowing full conversion of the ketone and lactone formation in a very short time (20 min, molar ratio Sn(OTf)(2):ketone:30 wt% aq. H2O2 = 0.1:1.0:2.0 at 70 degrees C) was reported for the first time. Next, Sn(OTf)(2) was used as an active phase and immobilized on various (nano)carbon materials. The application of the most active catalyst using multi-walled carbon nanotubes (MWCNTs) (length 1.5 mu m, outer diameter 9.5 nm) as a carrier allowed to reduce the amount of the active phase (Sn(OTf)(2)) to 0.26 mol% per ketone (full conversion of ketone to lactone was achieved after 20 min at 90 degrees C for molar ratio catalyst:ketone:30 wt% aq. H2O2: 0.0026:1.00:2.00, or full conversion of ketone to lactone was achieved after 1 h at 70 degrees C for molar ratio catalyst:ketone:60 wt% aq. H2O2: 0.0026:1.00:1.50). The superactivity was related to spherical nanosize Sn (OTf)(2) particles (ca. 2 nm) dispersed along the outer nanotube walls. The participation of both Lewis and Bronsted acids sites in the conversion of the ketone was postulated. A simple test with the generation of a retinyl cation shown that Sn(OTf)(2) underwent partial hydrolysis to triflic acid.